This invention is based upon the discovery by the inventors of the PKD2 gene associated with Autosomal Dominant Polycystic Kidney Disease (“ADPKD”), the “PKD2 gene” or “PKD2”, and a novel protein encoded by this gene. The discovery of the PKD2 gene and the protein encoded by the gene will have important implications in the diagnosis and treatment of ADPKD caused by defects in the PKD2 gene.
ADPKD is a genetically heterogeneous disorder that affects approximately 500,000 Americans and five million individuals world wide, and accounts for 8 to 10% of all end stage renal disease (ESRD) worldwide (Gabow, P. A. N. Eng. J. Med. 329:332 (1993)). Its principal clinical manifestation is bilateral renal cysts that result in chronic renal failure in about 45% of affected individuals by age 60 (Gabow, P. A., supra). Hypertension and liver cysts are common, and the involvement of other organ systems (Gabow, P. A., et al. Kidney Int. 38:1177 (1990); Chapman, A. B., et al. N. Eng. J. Med. 327:916 (1992); Hossack, K. F., et al. N. Eng. J. Med. 319:907 (1988); Torres, V. E., et al. Am. J. Kidney Dis. 22:513 (1993); Huston, J., et al. J. Am. Soc. Nephrol. 3:1871 (1993); Somlo, S., et al. J. Am. Soc. Nephrol. 4:1371 (1993)) lends support to the view that polycystic kidney disease is a systemic disorder (Gabow, P. A., supra).
To date, most forms of ADPKD have been associated with two genes, PKD1 and PKD2. The full genomic structure and cDNA sequence for the PKD1 gene has been identified (The International Polycystic Kidney Disease Consortium, Cell 81:289 (1995); The American PKD1 Consortium, Hum. Mol. Genet. 4:575 (1995)). Mutations in the PKD1 gene are suspected of causing 80-90% of all cases of ADPKD. The PKD2 gene has been localized on chromosome 4q21-23 and accounts for approximately 15% of affected families (Kimberling, W. J., et al. Genomics 18:467 (1993); Peters, D. J. M. and L. A. Sandkuijl Contrib. Nephrol. 97:128 (1992)). Prior to the present invention, however, the PKD2 gene had not been identified.